All sanding tools create a large amount of dust. In particular, a belt sander creates large quantities of wood dust both in the air and on the surface of the workpiece. Because of this most electric sanders employ some sort of dust collection system. These dust collection systems typically use a fan driven directly by the motor to create a suction for the dust collection system. The dust collection fan may be half of a two-sided or double sided fan (the other half cooling the motor) or it may be mounted on one end of a motor opposite to the other end bearing a motor cooling fan. In either case, dust laden air is deliberately routed past the motor and dust leakage into the motor is aggravated.
Furthermore, these systems tend to clog due to the tortuous flow path though and around narrow channels, small chokes, and tight corners. Clogging of the dust removal flow path not only degrades or stops dust collection, it can also foul the dust fan, load down the motor, and reduce cooling air to the sander motor, which may damage the motor. Another drawback of those systems employing a main motor fan to collect dust is that, when the user would prefer to work without dust collection, such systems cannot be deliberately shut off, because of the need to cool the motor. Simply leaving off the dust receptacle is often impractical since a stream of dust laden air would then exhaust at or near the user.
In some sanders such as the Black & Decker model 4028, a second, separately controllable electric motor and fan is provided for the dust collection system. The inclusion of a separate dust collection motor, however, drives up the size, weight, and cost of the sander.
Accordingly, it is an object of the present invention to provide an improved sander that provides a dust collection system wherein an obstruction of the dust removal path does not reduce cooling air flow to the motor. It is another object of the present invention to provide a sander dust collection system that allows for operation of the sander with the dust collection airflow deliberately blocked or stopped.
Another problem with current sander designs is the common use of so called “flag bag” dust receptacles. Flag bag receptacles are fabric dust bags usually suspended from a support over the top of the sander or set off to one side. The height of the bag and the location create problems with tool access to and with user vision of the workpiece. As the bag fills with dust the added weight can unbalance a type of portable tool that is often already top heavy. Furthermore, as it fills the bag will often droop down into dragging contact with the workpiece, which can damage the bag or pull the sander from the intended track.
Accordingly it is another objective of the present invention to provide a dust receptacle that will not droop or sag when loaded and which can be securely mounted low down and behind the main body of the belt sander.
Still another problem with current sanders is that the inlet of the dust receptacle and the dust outlet of the tool usually rely on a simple friction or taper fit to hold the two conical or tubular components together. Without a positive locking mechanism to hold the two parts together, it is possible for the two parts to separate during use, resulting in dust laden air blowing out of the suddenly exposed dust outlet.
Accordingly it is still another objective of the present invention to provide a secure mechanical engagement between the improved dust receptacle and to provide a positive locking mechanism to prevent the inadvertent disengagement of the dust receptacle from the sander.